Abstract: Disclosed is an apparatus and process for generation of thermal energy, and cogeneration which includes a variable speed rotating heat transfer apparatus for the fluidization and combustion of carbonaceous fuel. The apparatus has an integrally formed water cooled jacket and water cooled auger and is maintained at an inclination with respect to ground level. The apparatus and process allow for a wide range turndown ratio and is adapted to cause a multidirectional movement of the fuel to be combusted.